JP5016206B2 - RESIN COMPOSITION FOR REFLECTOR AND REFLECTOR COMPRISING THE SAME - Google Patents

Description

  The present invention relates to a resin composition for a reflector. More specifically, the present invention relates to a resin composition for a reflector that is a material for a reflector of a light-emitting diode, a reflector using the same, and a light-emitting diode.

  Since the 1990s, the progress of light emitting diodes (LEDs) has been remarkable. Among these, white LEDs are expected as next-generation light sources that replace conventional white light bulbs, halogen lamps, HID lamps, and the like. In fact, LEDs have been evaluated for their features such as long life, power saving, temperature stability, low voltage drive, etc., and are applied to displays, destination display boards, in-vehicle lighting, signal lights, emergency lights, mobile phones, video cameras, and the like.

Such a light-emitting device is usually manufactured by fixing an LED to a reflector (plate) formed by integrally molding a synthetic resin with a lead frame and sealing with a sealing material such as an epoxy resin or a silicone resin. The LED reflector material is required to have a high light reflectance in order to efficiently extract light emitted from the LED. Moreover, since there is an opportunity to be exposed to high temperatures such as a sealing process and a soldering process, high heat resistance is required.
Furthermore, it is desirable that the coefficient of thermal expansion is low so that peeling does not occur between the lead frame even if subjected to an abrupt heat cycle, and since the LED is sensitive to moisture, the reflector is required to have a low water absorption rate. It is done.
These are necessary physical properties even for reflectors for light emitting devices other than LEDs.

  As a resin composition for LED reflectors, for example, a resin composition in which a white pigment such as titanium oxide is blended with aromatic polyester or aromatic polyester amide (see Patent Document 1), a resin composition containing polyamide and titanium oxide ( Patent Document 2), and a resin composition for a reflector (see Patent Document 3) containing polyamide and potassium titanate fiber.

By the way, although it changes with sealing materials in the sealing process of LED, heat processing for several hours is normally performed at 100-200 degreeC. However, the materials disclosed in the above documents have a problem that they are colored by heat treatment at the time of sealing and the reflectance is greatly reduced.
Polyamide and polyester have a high water absorption rate, and when used as a reflector material, they may absorb moisture and damage the LED.
Japanese Patent Laid-Open No. 62-179780 JP-A-2-288274 JP 2002-294070 A

  The present invention has been made in view of the above-described problems, and provides a resin composition for a reflector that can suppress a decrease in reflectance of the reflector due to heat treatment during LED sealing and can reduce the water absorption rate of the reflector. Objective.

The inventors of the present invention have made extensive studies in order to solve the above problems. As a resin constituting the composition, when a styrenic polymer having a syndiotactic structure is used, reflection of the reflector by the sealing process is performed. The present inventors have found that the reduction of the rate can be suppressed and completed the present invention.
According to the present invention, the following resin composition for a reflector, a reflector, a light emitting diode, and a method for producing the same are provided.
1. The resin composition for reflectors containing the following (1) and (2).
(1) Styrene polymer having a syndiotactic structure: 30 to 99% by weight
(2) White pigment: 1 to 70% by weight
2. The reflection according to 1, wherein the white pigment is one or more compounds selected from the group consisting of titanium dioxide, alumina, zinc oxide, silicon dioxide, calcium carbonate, barium sulfate, potassium titanate, mica, kaolin, and talc. Resin composition for body.
3. (1) 30 to 80% by weight of a styrenic polymer having a syndiotactic structure, and (2) 1 to 60% by weight of a white pigment, and 5 to 5% of an inorganic compound having an aspect ratio of 5 or more 3. The resin composition for reflectors according to 1 or 2, comprising 40% by weight.
4). The inorganic compound having an aspect ratio of 5 or more is selected from the group consisting of glass fiber, potassium titanate whisker, silicon carbide whisker, aluminum borate whisker, calcium carbonate whisker, wollastonite, glass flake, and nanoclay. The resin composition for reflectors according to any one of 1 to 3, which is a compound of at least one species.
5. The reflector which consists of a resin composition for reflectors in any one of said 1-4.
6. The reflector according to 5, wherein the decrease in reflectance at a wavelength of 450 nm before and after the heat treatment at 160 ° C. for 3 hours is 10% or less.
7). The reflector according to 5 or 6, wherein the water absorption measured in accordance with JIS K7209 is 0.12% or less.
8). 8. A light emitting diode comprising the reflector according to any one of 5 to 7, a light emitting element formed on the reflector, and a sealing portion covering the light emitting element.
9. 9. The light emitting diode according to 8, wherein the sealing portion is made of epoxy resin, acrylic resin, or silicone resin.
10. The method for producing a light-emitting diode according to 8 or 9, comprising a step of heating to a temperature of 10.150 ° C. or more to cure the thermosetting resin to form a sealing portion.

  In the resin composition for reflectors of the present invention, the decrease in reflectance of the reflector due to heat treatment during LED sealing can be reduced, and the water absorption of the reflector can be lowered.

Hereinafter, the resin composition for a reflector of the present invention will be specifically described.
The reflector resin composition of the present invention includes the following components (1) and (2).
(1) Styrene polymer having a syndiotactic structure: 30 to 99% by weight
(2) White pigment: 1 to 70% by weight

  The styrenic polymer having a syndiotactic structure as component (1) is a syndiotacticity whose tacticity determined by nuclear magnetic resonance (NMR) is 85% or more for diat or 50% or more for pentad. Means having

  Specific examples of such styrenic polymers include polystyrene, poly (methylstyrene), poly (dimethylstyrene), poly (alkylstyrene) such as poly (t-butylstyrene), poly (chlorostyrene), Poly (halogenated styrene) such as poly (bromostyrene), poly (fluorostyrene), poly (o-methyl-p-fluorostyrene), poly (halogen-substituted alkylstyrene) such as poly (chloromethylstyrene), poly ( Methoxy styrene), poly (alkoxy styrene) such as poly (ethoxy styrene), poly (carboxy ester styrene) such as poly (carboxymethyl styrene), poly (alkyl ether styrene) such as poly (vinyl benzyl propyl ether), poly ( Poly (alkyl) such as trimethylsilylstyrene) Silyl styrene), poly (vinyl sulfonic acid ethyl), poly (vinylbenzyl methoxide diphosphite sulfide) and the like. Further, a mixture thereof, a copolymer having these as a main component, or the like may be used.

  As described above, the styrenic polymer having a highly syndiotactic structure in the present invention is not necessarily a single compound as described above. As long as the syndiotacticity is within the above range, it may be incorporated in a mixture or copolymer chain with a styrene polymer having an isotactic or atactic structure. The styrene copolymer may be a mixture of different molecular weights, and the degree of polymerization is at least 5 or more, preferably 10 or more. If the degree of polymerization is less than 5, the strength may be insufficient.

  The styrenic polymer having a syndiotactic structure can be produced by various methods, and the method described in JP-A No. 62-187708 is preferable.

  As the white pigment of component (2), titanium dioxide, zinc oxide, alumina, silicon dioxide, antimony oxide, cerium oxide, tin oxide, calcium carbonate, barium carbonate, magnesium carbonate, calcium sulfate, barium sulfate, potassium titanate, titanium Known white pigments such as potassium lithium oxide, magnesium potassium titanate, zinc white, talc, mica and kaolin can be used. Of these, titanium dioxide, zinc oxide, alumina, silicon dioxide, calcium carbonate, barium sulfate, potassium titanate, talc, mica, and kaolin are preferable, and more preferable compounds are titanium dioxide, zinc oxide, and potassium titanate.

Content of the styrenic polymer which has a syndiotactic structure is 30 to 99 weight% with respect to the whole resin composition. Preferably, it is 40 to 95% by weight. If it is less than 30% by weight, the strength may be insufficient. If it exceeds 95% by weight, the reflectance due to heat treatment may decrease.
The content of the white pigment is preferably 1 to 70% by weight, more preferably 3 to 60% by weight, based on the entire resin composition. If it is less than 1% by weight, the reflectance may be lowered. If it exceeds 70% by weight, the moldability may deteriorate.

The resin composition of the present invention preferably contains an inorganic compound having an aspect ratio of 5 or more. Thereby, the linear expansion coefficient of a reflector can be made low. For example, the linear expansion coefficient in the flow direction at the time of molding can be 5 × 10 ⁻⁵ K ⁻¹ or less. More preferably, the aspect ratio is 10 or more.
Examples of the inorganic compound having an aspect ratio of 5 or more include glass fiber, potassium titanate whisker, silicon carbide whisker, aluminum borate whisker, calcium carbonate whisker, wollastonite, glass flake, and nanoclay. Preferred compounds are glass fibers, potassium titanate whiskers, wollastonite, glass flakes and nanoclays.
The blending amount of the inorganic compound is preferably 5 to 30% by weight. If it is less than 5% by weight, the effect of decreasing the linear expansion coefficient may be insufficient. If it exceeds 30% by weight, the moldability may deteriorate.

  In the resin composition of the present invention, various additives (crystal nucleating agent, antioxidant, light stabilizer, lubricant, plasticizer, antistatic agent, release agent, etc.) can be blended as necessary. Moreover, you may mix | blend another thermoplastic resin and a compatibilizing agent.

  Examples of the thermoplastic resin include polyphenylene ether, polyolefin such as polyethylene, polypropylene and polypentene, polyester such as polyethylene terephthalate and polybutylene terephthalate, polythioether such as polyphenylene sulfide, polyamide, polycarbonate, polyethersulfone, polyimide, polyamideimide, Polymethyl methacrylate, ethylene-acrylic acid copolymer, acrylonitrile-styrene copolymer, acrylonitrile-chlorinated polyethylene-styrene copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, acrylonitrile-butadiene -Styrene copolymer, vinyl chloride resin, chlorinated polyethylene, fluorinated polyethylene, polyacetal, thermoplastic polyurea Emissions elastomers, polybutadiene, styrene-based elastomer (SBR, SBS, SEBS, SEPS), styrene - maleic anhydride copolymer and the like.

  Although it does not specifically limit as a compatibilizing agent, The modified body of a polyphenylene ether polymer is preferable. In particular, poly (2,6-dimethylenephenylene-1,4-ether) -based materials, maleic anhydride, maleic acid, fumaric acid, maleimide, maleic hydrazide, amino groups, carboxylic acid groups, hydroxyl groups, epoxy groups Those in which etc. are introduced are preferred.

  The resin composition of the present invention is blended in a predetermined ratio with each of the above essential components and optionally used additional components, for example, a suitable temperature by a Banbury mixer, a single screw extruder, a twin screw extruder, For example, it can prepare by fully knead | mixing at the temperature of the range of 270-320 degreeC.

The resin composition of the present invention can be molded into a desired shape by various molding methods. For example, it can be molded by putting the above composition granulated into pellets into an injection molding machine or the like.
The resin composition of the present invention is particularly suitable as a raw material for a reflector that reflects light emitted from various light-emitting elements. That is, the reflector obtained by molding the resin composition of the present invention has excellent heat resistance, and even when subjected to heating by the sealing step of the light emitting element, the reflectance is small. As a result, specifically, the reflectance of light having a wavelength of 450 nm when the heat treatment is performed at 160 ° C. for 3 hours can be reduced to 10% or less (more preferably 8% or less). The heat treatment conditions are set in consideration of the heating conditions in the light emitting element sealing step.
Further, the water absorption rate of the reflector can also be 0.12% or less (more preferably, 0.1% or less). The water absorption rate of the reflector is a value measured according to JIS K7209.

Next, an example of a light emitting diode using the reflector of the present invention will be described with reference to the drawings.
1A and 1B are schematic views showing an embodiment of a reflector of the present invention, where FIG. 1A is a top view and FIG. 1B is a cross-sectional view.
The reflector 11 is manufactured by being integrally molded with the lead frame 12. The lead frame 12 has conductivity to apply a voltage to the light emitting element, and is incorporated into the reflector 11 in two parts.
The size of the reflector is very small with a few millimeters. For example, there are cases where three sides (vertical × horizontal × height) are each about 3 mm.

FIG. 2 is a schematic cross-sectional view of an embodiment of a light emitting diode of the present invention.
The light emitting diode includes a reflector 11 formed integrally with the lead frame 12, a light emitting element (chip) 13 and a gold wire 14 formed on the lead frame 12, and a sealing portion 15 covering the element.
The reflector 11 efficiently reflects the light emitted from the light emitting element 13 to the outside of the light emitting diode. The light emitting element 13 is an element that emits light when a voltage is applied via the lead frame 12. The sealing part 15 protects the light emitting element 13 from the external environment.

In the light emitting diode of the present invention, a known semiconductor light emitting element can be used as the light emitting element 13 without any problem. The emission color is not limited.
As the lead frame 12, copper, silver, iron, palladium or the like can be used.
As the sealing part 15, epoxy resin, silicone resin, acrylic resin, phenol resin, urethane resin, diallyl phthalate resin, or the like can be used. These can be formed by curing a liquid (oligomeric) thermosetting resin. Of these, highly transparent and highly durable epoxy resins, acrylic resins, and silicone resins are preferable. In order to fully exhibit the characteristics of these resins, it is necessary to increase the degree of curing as much as possible. For that purpose, it is necessary to perform a curing treatment at a high temperature, but by using the reflector of the present invention, it is possible to reduce the deterioration of the reflection performance of the reflector due to the heat treatment.

The light emitting diode of the present invention can be produced by a known method except that the above-described reflector of the present invention is used. Specifically, after the light emitting element 13 is fixed on the lead frame 12, a thermosetting resin is supplied so as to cover the light emitting element 13 and is heated and cured.
In the manufacturing method of this invention, it has the process of heating and hardening a thermosetting resin to the temperature of 150 degreeC or more (250 degrees C or less), and forming a sealing part. Since the reflector of the present invention has sufficient resistance to heating during the sealing process, the decrease in reflectance caused by heating during the sealing process is small. Therefore, even if the sealing portion is formed on the reflector at a high temperature, the light emitting diode can be manufactured while maintaining excellent reflectivity.

Hereinafter, the present invention will be described more specifically with reference to examples.
Synthesis example [Synthesis of syndiotactic polystyrene]
To the reaction vessel, 320 L of toluene as a solvent, 13.35 mol of methylaluminoxane as a catalyst component as aluminum atoms, and 0.134 mol of tetraethoxytitanium were added, and then 150 kg of styrene was added thereto.
Next, the temperature was raised to 55 ° C., and a polymerization reaction was carried out for 2 hours. After completion of the reaction, the resulting product was washed with a sodium hydroxide-methanol mixed solution to decompose and remove the catalyst component. Next, this was dried to obtain 21 kg of a polymer.

This polymer was Soxhlet extracted using methyl ethyl ketone as a solvent to obtain an extraction residue of 95% by weight.
The polymer thus obtained had a weight average molecular weight of 400,000 and a melting point of 270 ° C. Further, this polymer showed absorption at 145.35 ppm due to the syndiotactic structure from analysis by isotope carbon nuclear magnetic resonance ( ¹³ C-NMR), and syndiotacticity in the pentad calculated from the peak area. The city was 98%.

Examples 1-6
After blending in the ratio shown in Table 1 and dry blending, it was put into a hopper of a twin screw extruder having an inner diameter of 30 mm, melt kneaded at a barrel temperature of 285 ° C., and formed into pellets.
The obtained pellets were dried at 70 ° C. for a whole day and night, and then injection molded at a barrel temperature of 280 ° C. and a mold temperature of 120 ° C. to obtain several square plate-like reflectors of 5 cm square and 3 mm thickness.

This reflector was heat-treated using a jet oven. The conditions were set to 160 ° C. for 3 hours, or set to 190 ° C. for 5 hours.
For the reflector before and after the heat treatment, the change in reflectance was evaluated. Moreover, the water absorption rate and the linear expansion coefficient of the reflector were measured. The measuring method is as follows. The measurement results are shown in Table 2.

(1) Measurement of reflectance The initial reflectance and the reflectance after heat treatment were measured by the following methods.
Shimadzu Corporation, self-recording spectrophotometer UV-2400PC, Shimadzu Corporation, multi-purpose large sample chamber unit MPC-2200 type is mounted, and the reflectance (%) is measured in the wavelength range of 700 to 300 nm. Then, the reflectance at 450 nm was evaluated. In addition, barium sulfate was used as a reference. FIG. 2 shows a measurement example of Comparative Example 2.

(2) Measurement of water absorption rate Measured according to JIS K7209.
(3) Linear expansion coefficient The linear expansion coefficient of MD direction (resin flow direction) was measured in the range of 25-130 degreeC using the following apparatuses. The results are shown in Table 2.
Measuring device: TMA120 thermomechanical analyzer (trade name: SSC5200H disk station, manufactured by Seiko Instruments Inc.)

Comparative Examples 1-3
After blending in the ratio shown in Table 1 and dry blending, it was put into a hopper of a twin screw extruder having an inner diameter of 30 mm, and melt kneaded at a barrel temperature of 330 ° C. to obtain pellets.
The obtained pellets were dried at 120 ° C. for a whole day and night, and then injection molded at a barrel temperature of 330 ° C. and a mold temperature of 130 ° C. to obtain several square plates of 5 cm square and 3 mm thickness.
The obtained square plate was evaluated in the same manner as in Example 1. The results are shown in Table 2.

Examples 7-12
Each of the resin compositions shown in Examples 1 to 6 was injection molded to produce an integrally molded product of a lead frame and a reflector as shown in FIG. A light-emitting element (Nichia Corporation, NCCU033) is mounted on this molded product, and after bonding a gold wire, a silicone-based sealant (Nippon Pernox, XJL-0012A / XJL-0012B = 100/5 (mass ratio). )) Was put into the recess of the molded product, and the sealant was cured under conditions of 160 ° C. and 3 hours (see FIG. 2). The electronic parts thus obtained were energized and the luminance was examined visually. Table 3 shows the evaluation results.

Comparative Examples 4-6
An electronic component was produced in the same manner as in Examples 7 to 12 except that each of the resin compositions shown in Comparative Examples 1 to 3 was injection molded, and the luminance was examined. Table 3 shows the evaluation results.

  The resin composition for reflectors of the present invention is suitable as a material for LED reflectors. The light emitting diode using the reflector of the present invention can be suitably used for displays, destination display boards, in-vehicle lighting, signal lights, emergency lights, mobile phones, video cameras and the like.

It is the schematic which shows one Embodiment of the reflector of this invention, (a) is a top view, (b) shows sectional drawing. It is a schematic sectional drawing which shows one Embodiment of the light emitting diode of this invention. 10 is a chart obtained by reflectance measurement of Comparative Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Reflector 12 Lead frame 13 Light emitting element 14 Gold wire 15 Sealing part

Claims (9)

The resin composition for reflectors containing the following (1) and (2).
(1) Styrene polymer having a syndiotactic structure: 30 to 99% by weight
(2) Titanium oxide : 1 to 70% by weight (1) 30-80% by weight of a styrenic polymer having a syndiotactic structure, and (2) 1-60% by weight of titanium oxide ,
Further, the reflection-body resin composition according to claim 1, wherein the aspect ratio comprises an inorganic compound 5-40 wt% of 5 or more. The inorganic compound having an aspect ratio of 5 or more is selected from the group consisting of glass fiber, potassium titanate whisker, silicon carbide whisker, aluminum borate whisker, calcium carbonate whisker, wollastonite, glass flake, and nanoclay. The resin composition for a reflector according to claim 1, wherein the resin composition is one or more kinds of compounds. The reflector which consists of the resin composition for reflectors in any one of Claims 1-3 . The reflector according to claim 4 , wherein a decrease in reflectance at a wavelength of 450 nm before and after the heat treatment at 160 ° C. for 3 hours is 10% or less. The reflector according to claim 4 or 5, wherein the water absorption measured in accordance with JIS K7209 is 0.12% or less. A reflector according to any one of claims 4 to 6 ;
A light emitting device formed on the reflector;
A light emitting diode including a sealing portion covering the light emitting element. The light emitting diode according to claim 7 , wherein the sealing portion is made of an epoxy resin, an acrylic resin, or a silicone resin. The manufacturing method of the light emitting diode of Claim 7 or 8 including the process of heating to the temperature of 150 degreeC or more, hardening a thermosetting resin, and forming a sealing part.

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